The subject invention is directed to glass forming apparatus, and more particularly, to the blank mold station and/or blow mold station of an IS machine. The problem involved is how to apply a large clamping force of 2000 pounds or more to the mold holder arms without interfering with adjacent structure and at the same time providing for overtravel to automatically compensate for wear.
One solution to this problem is taught by U.S. Pat. No. 3,460,931. As disclosed therein, booster motors 100 and 102 are coupled to the mold holder arms to provide additional clamping force to resist forces tending to prematurely open the molds. Experience has shown that such booster motors are ineffective or severely limited in the clamping force which can be provided. Said patent is correct in its premise that the necessary clamping force should not be attained through enlargement of the motor means for opening and closing the mold holder arms. It is old in the art to apply the mold opening force and the mold closing force to an extension of the mold holder arms as shown in FIG. 5 of U.S. Pat. No. 3,591,358. The lastmentioned patent does not teach how to apply a clamping force separate and apart from the force which is utilized to open and close the mold holder arms.
The present invention is directed to a solution of this problem in a manner which is simple, inexpensive and reliable.